CN111367064B - Medium-wave infrared continuous zoom lens and imaging device - Google Patents
Medium-wave infrared continuous zoom lens and imaging device Download PDFInfo
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- CN111367064B CN111367064B CN201811591878.1A CN201811591878A CN111367064B CN 111367064 B CN111367064 B CN 111367064B CN 201811591878 A CN201811591878 A CN 201811591878A CN 111367064 B CN111367064 B CN 111367064B
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- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
- G02B15/16—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group
- G02B15/163—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having a first movable lens or lens group and a second movable lens or lens group, both in front of a fixed lens or lens group
- G02B15/167—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having a first movable lens or lens group and a second movable lens or lens group, both in front of a fixed lens or lens group having an additional fixed front lens or group of lenses
- G02B15/173—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having a first movable lens or lens group and a second movable lens or lens group, both in front of a fixed lens or lens group having an additional fixed front lens or group of lenses arranged +-+
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Abstract
The invention discloses a medium wave infrared continuous zoom lens, wherein a front fixed group, a zoom lens group, a compensation lens group, a rear fixed group and a secondary imaging lens group are coaxially and sequentially arranged from an object space to an image space, the front fixed group has positive focal power, the zoom lens group has negative focal power, the compensation lens group has positive focal power, the rear fixed group has positive focal power, the secondary imaging lens group has positive focal power, and the zoom lens group and the compensation lens group can axially move to realize continuous zooming. The medium-wave infrared continuous zoom lens has a compact structure and meets the cold diaphragm efficiency of 100%; the axial movement of the zoom lens group and the compensation lens group realizes the continuous zooming of the system, the zooming stroke is short, the curve is smooth, and the imaging quality is good in the full-focus range.
Description
Technical Field
The invention relates to the technical field of optical imaging, in particular to a medium-wave infrared continuous zoom lens and an imaging device.
Background
When the optical instrument is used in a large temperature range, the lens focal power can be changed due to the expansion with heat and contraction with cold of the lens barrel material and the optical material and the temperature refractive index coefficient of the optical material, so that the defocusing phenomenon is generated, and the optical system can be defocused due to the expansion with heat and contraction with cold of the lens barrel material, so that the imaging quality is reduced. In order to reduce the influence of temperature variation on the imaging quality of the infrared optical system, a athermal design, or a thermal difference elimination design, is required, that is, through certain mechanical, optical, electronic and other technologies, defocusing caused by temperature variation is compensated, so that the infrared optical system keeps stable imaging quality in a temperature interval with a large variation range. The current heat difference eliminating mode mainly comprises the following steps: electromechanical active athermal differential, mechanical passive athermal differential, and optical passive athermal differential.
When the focal length of the infrared continuous zooming optical system is continuously changed in a certain range, the image surface is stable and good image quality can be kept. The size of the image surface scenery is continuously variable, and the visual effect which cannot be achieved by a fixed-focus lens and a multi-gear zoom lens can be achieved, so that the purposes of searching for a target with a large view field and carefully observing the target with a small view field are achieved.
At present, domestic research on a medium-wave infrared continuous zooming optical system has been reported in documents. Chinese patent publication No. CN106526818 discloses a three-group linked compact high zoom ratio infrared connection zoom optical system. However, the system adopts a three-component zooming mode, the optical system has a complex structure and higher control precision requirement, and the first compensation lens 3 is processed with an aspheric surface on a monocrystalline silicon material, so that the difficulty of optical processing is increased.
In summary, the three-component compact zoom lens has the problems of complex structure, difficult adjustment and the like; the aspheric surface on the monocrystalline silicon material increases the difficulty of optical processing.
Disclosure of Invention
The embodiment of the invention provides a medium-wave infrared continuous zoom lens and an imaging device, which can realize compact lens structure and have medium-wave infrared continuous zooming capability.
A first aspect provides a medium wave infrared continuous zoom lens, wherein a front fixed group, a zoom lens group, a compensation lens group, a rear fixed group and a secondary imaging lens group are coaxially and sequentially arranged from an object side to an image side, the front fixed group has positive focal power, the zoom lens group has negative focal power, the compensation lens group has positive focal power, the rear fixed group has positive focal power, the secondary imaging lens group has positive focal power, and the zoom lens group and the compensation lens group can axially move to realize continuous zooming.
With reference to the implementation manner of the first aspect:
the front fixed group is a meniscus silicon positive lens with a convex surface facing the object space, and the front surface and the rear surface of the meniscus silicon positive lens are spherical surfaces;
or the rear fixed group is a lens with a meniscus positive focal power, the convex surface of the lens faces the object space, and the front surface of the lens with the meniscus positive focal power is a diffraction surface processed on an even-order aspheric substrate;
or the compensation lens group comprises a first compensation lens and a second compensation lens which are coaxially and sequentially arranged from an object side to an image side, wherein the first compensation lens is a double convex positive lens, and the second compensation lens is a meniscus positive lens convex to the image side;
or the zoom lens group comprises a first zoom lens, a second zoom lens and a third zoom lens which are coaxially and sequentially arranged from an object side to an image side; the first zoom lens is a meniscus negative lens convex to the object, the second zoom lens is a meniscus positive lens convex to the object, and the third zoom lens is a biconcave negative lens;
or the secondary imaging lens group comprises a first meniscus lens with positive focal power convex to the image side and a second meniscus lens with positive focal power convex to the image side and positioned on the image side of the first meniscus lens.
With reference to the implementation manner of the first aspect:
the front surface of the first zoom lens is an even-order aspheric surface, and the rear surface of the first zoom lens is a spherical surface; the front surface and the rear surface of the second zoom lens are spherical surfaces; the front surface of the third zoom lens is a spherical surface, and the rear surface of the third zoom lens is an even-order aspheric surface;
or, the first variable focus lens is made of a germanium material, the second variable focus lens is made of a silicon material, and the third variable focus lens is made of a germanium material.
With reference to the implementation manner of the first aspect:
the front surface and the rear surface of the first compensation lens are spherical surfaces; the front surface of the second compensation lens is a spherical surface, and the rear surface of the second compensation lens is an even-order aspheric surface;
or the first compensation lens is made of a silicon material, and the second compensation lens is made of a zinc selenide material.
With reference to the implementation manner of the first aspect:
the front surface side surface of the first meniscus lens is a diffraction surface processed on an even-order aspheric substrate, and the rear surface of the first meniscus lens is a spherical surface; the front surface of the second meniscus lens is an even aspheric surface, and the rear surface of the second meniscus lens is a spherical surface;
or, the first meniscus lens and the second meniscus lens are both germanium lenses.
With reference to the implementation manner of the first aspect, the equation of the even aspheric surface is:
in the formula, Z is a distance rise from a vertex of the aspherical surface when the aspherical surface is at a position having a height h in the optical axis direction. c is 1/r, r represents the radius of curvature of the mirror surface, k is conic coefficient, and A, B, C, D is a high-order aspheric coefficient.
With reference to the implementation manner of the first aspect:
the high-order aspheric coefficients of the equation for the front surface of the first zoom lens are: a is-7.45 e-06, B is-5.65 e-10, C is 1.17e-12, D is-9.43 e-16;
the high-order aspheric coefficients of the equation for the rear surface of the third zoom lens are: a is-4.90 e-06, B is-1.39 e-10, C is 5.19e-12, D is-7.96 e-15;
the high-order aspheric coefficients of the equation for the rear surface of the second compensation lens are: a is 1.10e-06, B is 2.76e-10, C is-1.38 e-12, D is 2.28 e-15;
the high-order aspheric coefficients of the equation for the front surface of the lens of positive meniscus power are: a is-2.23 e-07, B is-1.70 e-08, C is 7.71e-11, D is-2.15 e-13;
the high-order aspheric surface coefficient of the even-order aspheric surface equation of the first meniscus lens is as follows: a is-1.94 e-04, B is 3.26e-06, C is-1.10 e-06, D is 3.24 e-08;
the high-order aspheric surface coefficient of the even-order aspheric surface equation of the second meniscus lens is as follows: a is-9.9 e-05, B is 9.09e-07, C is-6.11 e-09, and D is-4.50 e-12.
With reference to the implementation manner of the first aspect, the equation of the diffraction surface is:
φ(h)＝α1h2+α2h4…
wherein alpha is1、α2Is the diffraction coefficient.
With reference to the implementation manner of the first aspect:
the diffraction coefficient of the equation for the diffractive surface of the front surface of the rear fixed set of lenses of positive meniscus power is: alpha is alpha1Is-1.48 e-04, alpha2Is-2.19 e-07;
the diffraction coefficient of the equation for the diffractive surface of the first meniscus lens is: alpha is alpha1Is-1.17 e-03, alpha2Is 5.23 e-06.
A second aspect provides an imaging device, which includes the above-mentioned medium wave infrared zoom lens and a medium wave infrared detector for receiving the image formed by the medium wave infrared zoom lens.
The invention has the beneficial effects that: the medium-wave infrared continuous zoom lens has a compact structure and meets the cold diaphragm efficiency of 100%; the axial movement of the zoom lens group and the compensation lens group realizes the continuous zooming of the system, the zooming stroke is short, the curve is smooth, and the imaging quality is good in the full-focus range.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts. Wherein:
fig. 1 is a schematic view of a telephoto path of the medium-wave infrared continuous zoom lens according to the embodiment of the invention.
Fig. 2 is a schematic diagram of a middle focus optical path of the medium-wave infrared continuous zoom lens according to the embodiment of the present invention.
FIG. 3 is a schematic short-focus optical path diagram of the medium-wave infrared continuous zoom lens according to the embodiment of the present invention.
FIG. 4 is a graph of MTF at 20 ℃ in telephoto for the intermediate wave infrared continuous zoom lens according to the embodiment of the present invention.
FIG. 5 is a MTF curve diagram of the mid-focus of the mid-wave infrared continuous zoom lens according to the embodiment of the present invention at 20 ℃.
FIG. 6 is a MTF curve under 20 ℃ of short focus for the middle-wave infrared continuous zoom lens according to the embodiment of the present invention.
FIG. 7 is a MTF curve under a condition of tele-40 ℃ of the intermediate-wave infrared continuous zoom lens according to the embodiment of the present invention.
FIG. 8 is a MTF curve diagram of the intermediate focus of the intermediate wave infrared continuous zoom lens according to the embodiment of the present invention at-40 ℃.
FIG. 9 is a MTF curve under the condition of-40 ℃ short focus of the intermediate wave infrared continuous zoom lens according to the embodiment of the present invention.
FIG. 10 is a graph of MTF at 80 ℃ in telephoto for the intermediate wave infrared continuous zoom lens according to the embodiment of the present invention.
FIG. 11 is a MTF curve diagram of the mid-focus of the mid-wave infrared continuous zoom lens according to the embodiment of the present invention at 80 ℃.
FIG. 12 is a MTF curve graph at 80 ℃ for short focus of the mid-wave infrared continuous zoom lens according to the embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 is a schematic view of a telephoto path of the medium-wave infrared continuous zoom lens according to the embodiment of the invention. Fig. 2 is a schematic diagram of a middle focus optical path of the medium-wave infrared continuous zoom lens according to the embodiment of the present invention. FIG. 3 is a schematic short-focus optical path diagram of the medium-wave infrared continuous zoom lens according to the embodiment of the present invention. For convenience of explanation, only portions related to the present invention are shown in the drawings. Referring to fig. 1, 2 and 3, the medium wave infrared continuous zoom lens according to the embodiment of the present invention includes a front fixed group 110, a zoom lens group 120, a compensation lens group 130, a rear fixed group 140 and a secondary imaging lens group 150 coaxially and sequentially arranged from an object side to an image side, wherein the front fixed group 110 has positive focal power, the zoom lens group 120 has negative focal power, the compensation lens group 130 has positive focal power, the rear fixed group 140 has positive focal power, the secondary imaging lens group 150 has positive focal power, and the zoom lens group 120 and the compensation lens group 130 are axially movable to achieve continuous zooming. In the field of optical lens technology, it is a common technique how to implement moving zooming/focusing, for example, the zoom lens group 120 and the compensation lens group 130 can be mounted on a slidable or rolling track or device, and the moving or moving can be implemented by a stepping motor or other power device, therefore, the detailed description will not be provided in this section.
The medium wave infrared continuous zoom lens provided by the embodiment of the invention adopts five groups of lenses, has simple and reasonable structural design and very compact volume, meets the requirement of 100% of cold diaphragm efficiency, realizes continuous zooming of a system by the axial movement of the zoom lens group and the compensation lens group, has short zooming stroke and smooth curve, has good imaging quality in a full focus range, and is beneficial to batch production of lenses.
The lens group described in the present invention may be a single lens in this embodiment or other embodiments, or may be a lens group composed of several lenses. According to the direction of the light path, the left side surface of all optical elements in the diagram is defined as a front surface, and the right side surface of all optical elements in the diagram is defined as a rear surface; the left side is defined as the object side, and the right side is defined as the image side.
Specifically, this embodiment preferably:
the front fixed group 110 is a positive meniscus silicon lens 110 with a convex surface facing the object, the front fixed group 110 is a fixed lens, that is, the position of the positive meniscus silicon lens 110 in the lens is fixed, and the mid-wave infrared light is converged by the positive meniscus silicon lens 110. The front and rear surfaces of the positive meniscus silicon lens 110 are spherical. The meniscus silicon positive lens 110 is further preferably made of silicon crystal material, which is convenient for processing and production and has stable optical quality.
The zoom lens group 120 includes a first zoom lens 121, a second zoom lens 122, and a third zoom lens 123 which are coaxially arranged in this order from the object side to the image side; the first zoom lens 121 is a meniscus negative lens convex toward the object, the second zoom lens 122 is a meniscus positive lens convex toward the object, and the third zoom lens 123 is a biconcave negative lens. Preferably, the front surface of the first zoom lens 121 is an even-order aspherical surface, and the rear surface is a spherical surface; the front and rear surfaces of the second zoom lens 122 are spherical; the front surface of the third zoom lens 123 is a spherical surface, and the rear surface is an even-order aspherical surface. The first variable focal length lens 121 is made of a germanium material, the second variable focal length lens 122 is made of a silicon material, and the third variable focal length lens 123 is made of a germanium material. The zoom lens group 120 is used for changing the focal length and the variable magnification of the medium-wave infrared continuous zoom lens. The moving stroke of the variable focus lens assembly 120 is 40.10mm, which satisfies the requirement of large-range zooming. All lens materials of the variable focus lens group 120 are crystal materials, so that the processing and the production are convenient, and the optical quality is stable.
The compensation lens group 130 includes a first compensation lens 131 and a second compensation lens 132 coaxially arranged in order from an object side to an image side, the first compensation lens 131 is a double convex positive lens, and the second compensation lens 132 is a positive meniscus lens convex to the image side. The first compensation lens 131 is made of a silicon material, and the second compensation lens 132 is made of a zinc selenide material. The moving stroke of the compensation lens group 130 is 27.95mm, which satisfies the requirement of zooming in a larger range. The lens material of the biconvex positive lens 130 is preferably a crystalline material, which facilitates processing and production and has stable optical quality. The compensation lens group 130 is used for compensating the image plane position offset of the medium wave infrared continuous zoom lens in the zooming process.
The axial movement of the zoom lens group 120 and the compensation lens group 130 realizes the continuous zooming of the medium wave infrared continuous zoom lens, and the zooming stroke is short and the curve is smooth.
The rear fixed group 140 is a positive meniscus lens 140 with the convex surface facing the object, and the rear fixed group 140 is also a fixed lens group. The front surface of the positive meniscus lens 140 (i.e., the object side surface of the rear fixed group 140) is a diffractive surface machined on an even-order aspheric substrate, and the rear surface is spherical. The front surface has a base even-order aspheric surface and a diffractive surface machined on the base, so that the surface is constrained by both the even-order aspheric equation and the diffractive equation. The material of the positive meniscus lens 140 is preferably zinc sulfide or zinc selenide, and is further preferably zinc sulfide crystal material or zinc selenide crystal material, so that the processing and production are convenient, and the optical quality is stable.
After being focused by the front four groups of optical elements such as the meniscus silicon positive lens 110, the zoom lens group 120, the compensation lens group 130, the meniscus positive lens 140 and the like, the medium wave infrared light forms an intermediate image behind (i.e. on the image side) the meniscus positive lens 140; the secondary imaging lens group 150 is disposed behind the intermediate image. In the following detailed description, the intermediate image is preferably formed 17.90mm behind the meniscus positive lens 140, and the secondary imaging lens 150 set is disposed 2.60mm behind the intermediate image, which makes the medium wave infrared zoom lens structure more compact.
The secondary imaging lens group 150 includes a second meniscus lens 152 of positive power convex to the image side and a first meniscus lens 151 of positive power convex to the image side on the image side of the second meniscus lens 152. The first meniscus lens 151 and the second meniscus lens 152 are both germanium lenses, and further preferably germanium crystal lenses, which are convenient for processing and production and have stable optical quality. The front surface (i.e., the object side surface) of the first meniscus lens 151 is a diffractive surface machined on an even-order aspherical surface substrate (i.e., the front surface has a basic even-order aspherical surface and a diffractive surface machined on the basis), and the rear surface thereof is a spherical surface. The front surface (i.e., the object side surface) of the second meniscus lens 152 is an even-aspheric surface, and the rear surface thereof is a spherical surface. The secondary imaging lens group 150 can be used for focusing and compensating the drift of a focal plane in real time along with the temperature change, so that the heat dissipation difference of-40 ℃ to 80 ℃ is realized (the imaging definition can be still kept within the temperature range of-40 ℃ to 80 ℃), and therefore, the medium-wave infrared continuous zoom lens has good heat dissipation difference capacity and can also be called a compact heat dissipation difference medium-wave infrared continuous zoom lens.
In this embodiment, the lens uses nine lenses in total, the total optical length is only 172.3mm, all the lenses are made of crystal materials, and the diffraction surfaces of the rear fixed group 140 and the first meniscus lens 151 correct various aberrations well, so that the optical system has good quality, can zoom continuously within the range of 29.4mm to 470mm of focal length, and can realize compact thermal aberration elimination medium wave infrared continuous zooming high-definition imaging.
The aspheric surface of the lens is arranged on materials such as germanium, zinc selenide or zinc sulfide which are easy to carry out diamond single-point turning, the silicon lens in the optical system is spherical, the traditional optical cold machining grinding and polishing process can be adopted, and the machining difficulty is reduced.
The lens structure of the embodiment of the invention has simple and reasonable design and is beneficial to the batch production of the lens; the volume is very compact, and the applicability and the application range are greatly expanded.
The equation of the even aspheric surface related in the embodiment of the invention is as follows:
in the formula, Z is a distance rise from a vertex of the aspherical surface when the aspherical surface is at a position having a height h in the optical axis direction. c is 1/r, r represents the radius of curvature of the mirror surface, k is conic coefficient, and A, B, C, D is a high-order aspheric coefficient.
The equation for the diffraction surface involved in the embodiments of the present invention is:
φ(h)＝α1h2+α2h4…
wherein alpha is1、α2Is the diffraction coefficient.
According to the above equation and the spherical equation, the parameters of the embodiment of the present invention are as follows:
table 1, optical structure parameters of the inventive examples:
table 2, aspherical coefficients of examples of the present invention (surface numbers are the same as in table 1):
table 3, diffraction surface coefficients of the inventive examples (surface numbers same as table 1):
the lens of the medium-wave infrared continuous zoom lens provided by the embodiment of the invention is compact and has the heat difference eliminating capability, and specific lens parameters are shown in a table 4.
TABLE 4 lens parameters
The embodiment of the invention uses five groups of nine lenses together, all the lenses are made of crystal materials, a secondary imaging light path design is adopted, the lens materials, the radius, the distance and the thickness parameters are reasonably matched, the total optical length is only 172.3mm, the structure is compact, the working wave band is 3.4-5.0 μm, the F number is constant and is 4.0, the heat dissipation difference is-40-80 ℃, the cold diaphragm efficiency is 100 percent, the continuous zooming can be realized within the range of 29.4-470 mm of the focal length, the good imaging quality is realized within the full focus range, and the refrigeration medium wave infrared detectors with the resolution of 640 multiplied by 512, the pixel size of 15 μm, 20 μm and the like can be simultaneously adapted.
Fig. 4-6 are Modulation Transfer Function curves for the 20 c position for the tele, mid and short focus positions of the preferred embodiment of the present invention, and fig. 7-12 are Modulation Transfer Function curves for the-40 c and 80 c positions for the tele, mid and short focus positions of the preferred embodiment of the present invention. In the figure, the horizontal axis represents spatial frequency, unit: wire pairs per millimeter (lp/mm); and the value of a longitudinal axis surface Modulation Transfer Function (MTF) is used for evaluating the imaging quality of the lens, the value range is 0 to 1.0, the higher the MTF curve is, the straighter the MTF curve is, the better the imaging quality of the lens is, and the stronger the reduction capability of the real image is. As can be seen from fig. 4 to 6, the lens according to the embodiment of the present invention has excellent imaging capability at various focal lengths. As can be seen from FIGS. 7-12, after the lens compensates the drift of the focal plane, the lens assembly can be ensured to clearly image on the whole imaging surface under the environment of-40 ℃ to 80 ℃, and the requirement of poor heat dissipation is met.
Another embodiment of the present invention provides an imaging apparatus, which includes the above-mentioned medium wave infrared zoom lens and a medium wave infrared detector for receiving images formed by the medium wave infrared zoom lens. The medium wave infrared detector converts the image formed by the medium wave infrared continuous zoom lens into an electric signal for subsequent processing, and intelligent processing is realized. The imaging device may be a camera, a pod, or some other device or apparatus.
Further, the medium wave infrared detector is preferably a refrigeration medium wave infrared detector with the resolution of 640 x 512 and the pixel size of 15 μm or 20 μm, so that the adaptability of the imaging device of the embodiment of the invention is improved, and the popularization and the application are facilitated.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (8)
1. A medium wave infrared continuous zoom lens is characterized in that a front fixed group, a zoom lens group, a compensation lens group, a rear fixed group and a secondary imaging lens group are coaxially and sequentially arranged from an object side to an image side, the front fixed group has positive focal power, the zoom lens group has negative focal power, the compensation lens group has positive focal power, the rear fixed group has positive focal power, the secondary imaging lens group has positive focal power, and the zoom lens group and the compensation lens group can axially move to realize continuous zooming;
the front fixed group is a meniscus silicon positive lens with a convex surface facing the object space, and the front surface and the rear surface of the meniscus silicon positive lens are spherical surfaces;
the rear fixed group is a lens with a meniscus positive focal power, the convex surface of the lens faces the object space, and the front surface of the lens with the meniscus positive focal power is a diffraction surface processed on an even-order aspheric substrate;
the compensation lens group comprises a first compensation lens and a second compensation lens which are coaxially and sequentially arranged from an object side to an image side, the first compensation lens is a double convex positive lens, and the second compensation lens is a meniscus positive lens convex to the image side;
the zoom lens group comprises a first zoom lens, a second zoom lens and a third zoom lens which are coaxially and sequentially arranged from an object side to an image side; the first zoom lens is a meniscus negative lens convex to the object, the second zoom lens is a meniscus positive lens convex to the object, and the third zoom lens is a biconcave negative lens;
the secondary imaging lens group comprises a first meniscus lens with positive focal power protruding to the image side and a second meniscus lens with positive focal power protruding to the image side and positioned on the image side of the first meniscus lens;
the front surface of the first zoom lens is an even-order aspheric surface, and the rear surface of the first zoom lens is a spherical surface; the front surface and the rear surface of the second zoom lens are spherical surfaces; the front surface of the third zoom lens is a spherical surface, and the rear surface of the third zoom lens is an even-order aspheric surface;
the first zoom lens is made of a germanium material, the second zoom lens is made of a silicon material, and the third zoom lens is made of a germanium material;
the moving stroke of the zoom lens group is 40.10 mm.
2. The medium wave infrared zoom lens of claim 1, wherein:
the front surface and the rear surface of the first compensation lens are spherical surfaces; the front surface of the second compensation lens is a spherical surface, and the rear surface of the second compensation lens is an even-order aspheric surface;
or the first compensation lens is made of a silicon material, and the second compensation lens is made of a zinc selenide material.
3. The medium wave infrared zoom lens of claim 1, wherein:
the front surface side surface of the first meniscus lens is a diffraction surface processed on an even-order aspheric substrate, and the rear surface of the first meniscus lens is a spherical surface; the front surface of the second meniscus lens is an even aspheric surface, and the rear surface of the second meniscus lens is a spherical surface;
or, the first meniscus lens and the second meniscus lens are both germanium lenses.
4. The medium wave infrared continuous zoom lens of any one of claims 1 to 3, wherein the equation for the even aspheric surface is:
where Z is a height of h from the aspheric surface along the optical axis, c is 1/r, r represents a curvature radius of the mirror surface, k is conic coefficient conc, and A, B, C, D is a high-order aspheric coefficient.
5. The medium wave infrared zoom lens of claim 4, wherein:
the high-order aspheric coefficients of the equation for the front surface of the first zoom lens are: a is-7.45 e-06, B is-5.65 e-10, C is 1.17e-12, D is-9.43 e-16;
the high-order aspheric coefficients of the equation for the rear surface of the third zoom lens are: a is-4.90 e-06, B is-1.39 e-10, C is 5.19e-12, D is-7.96 e-15;
the high-order aspheric coefficients of the equation for the rear surface of the second compensation lens are: a is 1.10e-06, B is 2.76e-10, C is-1.38 e-12, D is 2.28 e-15;
the high order aspheric coefficients of the equation for the front surface of the rear fixed set of meniscus positive power lenses are: a is-2.23 e-07, B is-1.70 e-08, C is 7.71e-11, D is-2.15 e-13;
the high-order aspheric surface coefficient of the even-order aspheric surface equation of the first meniscus lens is as follows: a is-1.94 e-04, B is 3.26e-06, C is-1.10 e-06, D is 3.24 e-08;
the high-order aspheric surface coefficient of the even-order aspheric surface equation of the second meniscus lens is as follows: a is-9.9 e-05, B is 9.09e-07, C is-6.11 e-09, and D is-4.50 e-12.
6. The medium wave infrared zoom lens of claim 3, wherein the equation for the diffractive surface is:
φ(h)＝α1h2+α2h4…；
wherein alpha is1、α2Is the diffraction coefficient.
7. The medium wave infrared zoom lens of claim 6, wherein:
the diffraction coefficient of the equation for the diffractive surface of the front surface of the rear fixed set of lenses of positive meniscus power is: alpha is alpha1Is-1.48 e-04, alpha2Is-2.19 e-07;
the diffraction coefficient of the equation for the diffractive surface of the first meniscus lens is: alpha is alpha1Is-1.17 e-03, alpha2Is 5.23 e-06.
8. An imaging apparatus, comprising the medium wave infrared zoom lens system according to any one of claims 1 to 7 and a medium wave infrared detector for receiving an image formed by the medium wave infrared zoom lens system.
Priority Applications (1)
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| JP2011053526A (en) * | 2009-09-03 | 2011-03-17 | Kinoshita Optical Research Institute Co Ltd | Zoom lens |
| CN102401983A (en) * | 2011-12-27 | 2012-04-04 | 河南中光学集团有限公司 | Optical system with infrared continuous zoom lenses |
| CN203981958U (en) * | 2014-06-26 | 2014-12-03 | 北京蓝思泰克科技有限公司 | A kind of large zoom ratio medium wave infrared continuous zoom lens |
| KR20160141103A (en) * | 2015-05-28 | 2016-12-08 | (주)토핀스 | 10 cooled thermal imaging camera mwir 10 magnification continuous zoom opticals system |
| CN207216116U (en) * | 2017-08-22 | 2018-04-10 | 三河市蓝思泰克光电科技有限公司 | One kind miniaturization salt free ligands face medium-wave infrared double-view field camera lens |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011053526A (en) * | 2009-09-03 | 2011-03-17 | Kinoshita Optical Research Institute Co Ltd | Zoom lens |
| CN102401983A (en) * | 2011-12-27 | 2012-04-04 | 河南中光学集团有限公司 | Optical system with infrared continuous zoom lenses |
| CN203981958U (en) * | 2014-06-26 | 2014-12-03 | 北京蓝思泰克科技有限公司 | A kind of large zoom ratio medium wave infrared continuous zoom lens |
| KR20160141103A (en) * | 2015-05-28 | 2016-12-08 | (주)토핀스 | 10 cooled thermal imaging camera mwir 10 magnification continuous zoom opticals system |
| CN207216116U (en) * | 2017-08-22 | 2018-04-10 | 三河市蓝思泰克光电科技有限公司 | One kind miniaturization salt free ligands face medium-wave infrared double-view field camera lens |
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